The proposed research is designed to investigate the use of acoustic cues for speech recognition by normal-hearing and hearing-impaired listeners. Recent studies have emphasized the significance of short-term onset spectra for the perception of consonant place of articulation. Using synthetic speech, experiments will be conducted to determine whether hearing-impaired listeners are able to utilize these "invariant" cues for consonant recognition, or instead, must rely on additional context-dependent cues such as formant transitions. A major assumption is that specific abnormalities of auditory frequency and temporal analysis, which often accompany sensorineural hearing loss, result in an inability to make use of onset spectral cues for place perception. In addition, large differences in speech recognition performance are often observed even within a group of hearing-impaired listeners considered homogeneous on the basis of age, magnitude of loss, etiology, and anatomical location of lesion. This intersubject variability may reflect the large individual differences in frequency and temporal analysis dysfunction of hearing-impaired listeners. Results of psychoacoustic procedures to measure these phenomena will allow us to evaluate and classify hearing-impaired listeners using criteria which are more relevant to the understanding of their speech recognition deficit. The results of these studies should provide important information concerning the dynamics of the speech recognition deficit faced by the hearing-impaired. Ultimately, the results may influence the design of hearing-aid amplification devices and be of use to professionals who are responsible for auditory-training procedures with hearing-impaired individuals.